There is known a hybrid vehicle that includes a power transmission mechanism which is connected with an internal combustion engine, a motor generator, and an output member, and is capable of changing and transmitting to the output member, rotating speed of the internal combustion engine. Furthermore, in such a hybrid vehicle, there is known a vehicle which is capable of switching modes of the power transmission mechanism between a variable gear ratio mode where gear ratios are changeable continuously and a fixed gear ratio mode where gear ratio is fixed in an overdrive state where rotating speed of the internal combustion engine is lower than rotating speed of the output member. And, there is known a control apparatus including a map which shows correlation between an operating point of the vehicle which is specified by vehicle speed and target driving power, and an operating region where the mode should be switched to the variable gear ratio mode and an operating region where the mode should be switched to the fixed gear ratio mode, and switching the mode of the power transmission mechanism based on this map and the present operating point of the vehicle (see Patent Literature 1). In addition, there is Patent Literature 2 as prior art reference in relation to the present invention.